How to create instance variable and use inside the class?

Question

How to create an instance variable from the below list which contains a dictionary key called price and i am trying to retrieve the price list of all the books using a class called Library

1 ) Here is the list of books and their details

data = { "books" : [ { "number_of_pages" : 849,
        "price" : 13.550000000000001,
        "publish_date" : 2011,
        "subjects" : [ "Time travel",
            "Assassination"
          ],
        "title" : "11/22/63"
      },
      { "number_of_pages" : 732,
        "price" : 7.9900000000000002,
        "publish_date" : 1999,
        "subjects" : [ "Authors",
            "Custody of children",
            "Grandfathers",
            "Haunted houses",
            "Novelists",
            "Trials (Custody of children)",
            "Widowers",
            "Widows",
            "Writer's block"
          ],
        "title" : "Bag of bones"
      },]}

2 ) I created a class called Library which will unpack the list and store the variables

class Library:
    def __init__(self,**kwargs):

        for k, v in kwargs.items():
            setattr(self, k, v)
            #print(k,v)
        if 'price' in v[0:][1]:
              for c in v[0:][1].items():
                  if 'price' in c:
                    self.price=c['price']


    def price_book(self):
         return self.price

    def __float__(self):
        return self.price


Libra = Library(**data)
Price=Libra.price_book()
print(Price)

While trying to return using the instances its retuning the error for setting the variable for price ?

How to set the instance variable and retrieve list of prices in library ?

Regards

Update 1:

self.price=c['price']

TypeError: tuple indices must be integers or slices, not str

Update 2 :

class Library:
    def __init__(self,**kwargs):

        for k, v in kwargs.items():
                setattr(self, k, v)

        self.price = []
        for k, v in kwargs.items():
            for i in range(len(v)):
                self.price.append(v[i]['price'])

    def price_book(self):
         return self.price

    def discount_book(self):
         self.price=self.price
         return  list(map((lambda x: x -2), self.price))

    def __float__(self):
        return self.price

Libra = Library(**data)
Price=Libra.price_book()
Pri=Libra.discount_book()
print(Price)
print(Pri)

Answer 1

if 'price' in v[0:][1]:
    for c in v[0:][1].items():
        if 'price' in c:
            self.price=c['price']

The items() method of a dictionary returns key-value pairs as tuples.

Therefore c is a tuple such as ('price', 7.99) .

Tuples are indexed by integers, not strings.

You probably want self.price = c[1] instead.

Answer 2

Just having trouble seeing where you are hung up, if it's retrieving the prices or setting them to the instance.

def __init__(self, **kwargs):

    for k, v in kwarg.items():
        setattr(self, k, v)

    self.price = []
    for k, v in kwargs.items():
        for i in range(len(v)):
            self.price.append(v[i]['price'])

 (xenial)vash@localhost:~/python/AtBS$ python3.7 comphren.py [13.55, 7.99] 

Suggestion by Request

One thing I would I didn't do because I'm unsure I think the use of data creates unneeded nesting that unless you are going to have books and say movies otherwise you could just call this whole thing books and remove one level of nesting. Also this method logs duplicates, which I worked around using set but you could avoid appending duplicates with more code, didn't want to do too much because still unsure of entire task.

But if the goal was just to create these lists of each piece of data this code will work:

pages = []
publish_dates = []
subjects = []
titles = []
prices = []

for v in data.values():
    for i in range(len(v)):
       for w, x in v[i].items():
            pages.append(v[i]['number_of_pages'])
            publish_dates.append(v[i]['publish_date'])
            titles.append(v[i]['title'])
            prices.append(v[i]['price'])
            for a in v[i]['subjects']:
                subjects.append(a)

print(f"Pages: {set(pages)}\nPublish Dates: {set(publish_dates)}\n" \
      f"Subjects: {set(subjects)}\nTitles:{set(titles)}\n" \
      f"Prices: {set(prices)}")

Output

 (xenial)vash@localhost:~/python/AtBS$ python3.7 comphren.py Pages: {849, 732} Publish Dates: {2011, 1999} Subjects: {'Time travel', 'Widows', 'Authors', 'Widowers', 'Assassination', 'Haunted houses', 'Grandfathers', "Writer's block", 'Novelists', 'Trials (Custody of children)', 'Custody of children'} Titles:{'11/22/63', 'Bag of bones'} Prices: {13.55, 7.99}